23 States Sue Trump Administration Over Rollback of Core U.S. Climate Rule

A coalition of 23 U.S. states, led by New York and California, along with 14 cities and counties, has launched a major legal challenge against the Trump administration’s rollback of a foundational climate regulation.

The lawsuit, filed in the U.S. Court of Appeals for the District of Columbia Circuit, targets the U.S. Environmental Protection Agency’s decision to revoke the 2009 “endangerment finding”-a scientific determination that greenhouse gas emissions pose a threat to human health and the environment. This finding has long served as the legal basis for federal climate regulations.

The legal action also challenges the EPA’s move to repeal vehicle emissions standards covering model years 2012 to 2027, which had set limits on greenhouse gas pollution from cars and trucks.

Joining the lawsuit are several states, including Michigan, Connecticut, and Virginia, as well as major cities such as New York City, Los Angeles, and Chicago. Officials argue that dismantling the endangerment finding undermines the federal government’s ability to address climate change.

New York Attorney General Letitia James criticized the move, saying the administration is abandoning critical protections needed to confront climate risks. Environmental groups have also warned that rolling back emissions standards could increase fuel consumption and raise long-term costs for consumers.

The Trump administration has defended the repeal, calling the original finding an overreach that burdened industries and drove up prices. The EPA estimates the rollback could save $1.3 trillion over three decades.

This lawsuit marks the latest escalation in a widening legal battle between federal and state governments over climate policy, with courts now set to play a pivotal role in determining the future of U.S. environmental regulation.

Multi-state litigation over core climate rules shows how enforcement and rule-making are moving into private and state channels, and it creates uncertainty that corporates should be planning around. Our ESG-strategy and sustainability-due-diligence teams help US clients build disclosure and compliance infrastructure that stays robust across ongoing litigation.